Write coil cooling arrangement at air bearing surface

ABSTRACT

A slider comprises an air bearing surface (ABS) and is configured to interact with a magnetic recording medium. A writer is provided on the slider and comprises a write coil having a media-facing surface situated at the ABS. Cooling arms project laterally from peripheral surfaces of the write coil and extend along the ABS. The media-facing surface of the write coil and the cooling arms are exposed to the ABS to facilitate increased cooling of the write coil at the ABS.

RELATED PATENT DOCUMENTS

This application is as continuation of U.S. patent application Ser. No.15/001,475, filed Jan. 20, 2016, to which priority is claimed and whichis incorporated herein by reference in its entirety.

SUMMARY

Embodiments of the disclosure are directed to an apparatus comprising aslider having an air bearing surface (ABS) and configured to interactwith a magnetic recording medium. A writer is provided on the slider andcomprises a write coil having a media-facing surface situated at theABS. Cooling arms project laterally from peripheral surfaces of thewrite coil and extend along the ABS. The media-facing surface of thewrite coil and the cooling arms are exposed to the ABS to facilitatecooling of the write coil at the ABS.

Some embodiments are directed to an apparatus comprising a slider havingan ABS and configured to interact with a magnetic recording medium. Awriter is provided on the slider and comprises a write pole terminatingat or near the ABS, a return pole proximate the write pole, and a writecoil arrangement having a media-facing surface situated at the ABS. Thewrite coil arrangement comprise lower and upper write coils each havinga generally circularly-shaped periphery, a first peripheral surface, asecond peripheral surface, and a width defined between the first andsecond peripheral surfaces. The write coil arrangement also comprisescooling arms projecting laterally from the first and second peripheralsurfaces of the lower and upper write coils and extending along the ABS.The media-facing surface of the write coil arrangement and the coolingarms are exposed to the ABS to facilitate cooling of the write coilarrangement at the ABS.

Other embodiments are directed to an apparatus comprising a sliderhaving an ABS and configured to interact with a magnetic recordingmedium. A writer is provided on the slider and comprises a write poleterminating at or near the ABS, a return pole proximate the write pole,and a write coil having a media-facing surface situated at the ABS. Themedia-facing surface of the write coil is exposed to the ABS tofacilitate cooling of the write coil at the ABS.

The above summary is not intended to describe each disclosed embodimentor every implementation of the present disclosure. The figures and thedetailed description below more particularly exemplify illustrativeembodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a slider configured forheat-assisted magnetic recording (HAMR) in which the various embodimentsdisclosed herein may be implemented;

FIG. 2 shows a HAMR slider in accordance with various embodiments;

FIG. 3 illustrates a writer which incorporates a write coil coolingarrangement in accordance with various embodiments;

FIG. 4 illustrates a writer which incorporates a write coil coolingarrangement in accordance with some embodiments;

FIG. 5 illustrates a writer which incorporates a write coil coolingarrangement in accordance with other embodiments;

FIG. 6 is an exploded view of a cooling arm of a write coil coolingarrangement in accordance with various embodiments;

FIGS. 7 and 8 are views of a lower write coil that incorporates acooling arrangement in accordance with various embodiments;

FIGS. 9 and 10 are views of an upper write coil that incorporates acooling arrangement in accordance with various embodiments;

FIG. 11 is a view of a write coil having an outermost coil turn exposedto an ABS of the slider in accordance with various embodiments;

FIG. 12 illustrates a writer which incorporates a truncated write coilcooling arrangement in accordance with some embodiments;

FIGS. 13 and 14 illustrate an upper write coil of a writer thatincorporates a thickened cooling arrangement in accordance with someembodiments;

FIG. 15 illustrates a lower write coil of a writer that incorporates athickened cooling arrangement in accordance with some embodiments;

FIGS. 16 and 17 illustrate an upper write coil of a writer thatincorporates a thickened cooling arrangement coated with a ABS-friendlymetal or metal alloy in accordance with some embodiments;

FIG. 18 illustrates a lower write coil of a writer that incorporates athickened cooling arrangement coated with a ABS-friendly metal or metalalloy in accordance with some embodiments; and

FIG. 19 illustrates a writer coil arrangement which incorporates athermally conductive dielectric material disposed between a write coiland a cooling arm in accordance with various embodiments.

The figures are not necessarily to scale. Like numbers used in thefigures refer to like components. However, it will be understood thatthe use of a number to refer to a component in a given figure is notintended to limit the component in another figure labeled with the samenumber.

DETAILED DESCRIPTION

The present disclosure generally relates to writers of a magneticrecording head and, more particularly, to arrangements for dissipatingheat generated by writers during write operations. Embodiments of thedisclosure provide for a reduction in Writer-Induced-Writer Protrusion(WIWP) over conventional writer designs due to provision of a write coilcooling arrangement configured to dissipate heat at the air bearingsurface of the head. Writer cooling embodiments of the disclosure findparticular application in recording heads configured for heat-assistedmagnetic recording (HAMR), also referred to as energy-assisted magneticrecording (EAMR), thermally-assisted magnetic recording (TAMR), andthermally-assisted recording (TAR). Embodiments of the disclosure can beimplemented in conventional or HAMR heads.

Referring now to FIG. 1, a block diagram shows a side view of arecording head arrangement comprising a slider 102 according to arepresentative embodiment. The slider 102 may be used in a magnetic datastorage device, e.g., a hard disk drive. The slider 102 may also bereferred to herein as a recording head, a write head, or a read/writehead. The slider 102 is coupled to an arm 104 by way of a suspension 106that allows some relative motion between the slider 102 and arm 104. Theslider 102 includes read/write transducers 108 at a trailing edge thatare held proximate to a surface 110 of a magnetic recording medium 111,e.g., magnetic disk. The slider 102 is configured as a HAMR recordinghead, which includes a laser 120 (or other energy source) and awaveguide 122. The waveguide 122 delivers light from the laser 120 tocomponents near the read/write transducers 108.

When the slider 102 is located over surface 110 of recording medium 111,a flying height 112 is maintained between the slider 102 and the surface110 by a downward force of arm 104. This downward force iscounterbalanced by an air cushion that exists between the surface 110and an air bearing surface 103 (also referred to herein as a“media-facing surface”) of the slider 102 when the recording medium 111is rotating. It is desirable to maintain a predetermined slider flyingheight 112 over a range of disk rotational speeds during both readingand writing operations to ensure consistent performance. Region 114 is a“close point” of the slider 102, which is generally understood to be theclosest spacing between the read/write transducers 108 and the magneticrecording medium 111, and generally defines the head-to-medium spacing113. To account for both static and dynamic variations that may affectslider flying height 112, the slider 102 may be configured such that aregion 114 of the slider 102 can be configurably adjusted duringoperation in order to finely adjust the head-to-medium spacing 113. Thisis shown in FIG. 1 by a dotted line that represents a change in geometryof the region 114. In this example, the geometry change may be induced,in whole or in part, by an increase or decrease in temperature of theregion 114 via a heater 116.

FIG. 2 shows a recording head arrangement 200 configured forheat-assisted magnetic recording in accordance with various embodiments.The recording head arrangement 200 includes a slider 202 positionedproximate a rotating magnetic medium 211. The slider 202 includes areader 204 and a writer 206 proximate the ABS 215 for respectivelyreading and writing data from/to the magnetic medium 211. The writer 206is located adjacent an NFT 210 which is optically coupled to a lightsource 220 (e.g., laser diode) via a waveguide 222. The light source 220can be mounted externally, or integral, to the slider 202. The lightsource 220 energizes the NFT 210 via the waveguide 222.

A HAMR device utilizes the types of optical devices described above toheat a magnetic recording media (e.g., hard disk) in order to overcomesuperparamagnetic effects that limit the areal data density of typicalmagnetic media. When writing with a HAMR device, electromagnetic energyis concentrated onto a small hot spot 209 over the track of the magneticmedium 211 where writing takes place, as shown in FIG. 2. The light fromthe source 220 propagates to the NFT 210, e.g., either directly from thesource 220 or through the mode converter or by way of a focusingelement. Other optical elements, such as couplers, mirrors, prisms,etc., may also be formed integral to the slider. As a result of what isknown as the diffraction limit, optical components cannot be used tofocus light to a dimension that is less than about half the wavelengthof the light. The lasers used in some HAMR designs produce light withwavelengths on the order of 700-1550 nm, yet the desired hot spot 209 ison the order of 50 nm or less. Thus, the desired hot spot size is wellbelow half the wavelength of the light. Optical focusers cannot be usedto obtain the desired hot spot size, being diffraction limited at thisscale. As a result, the NFT 210 is employed to create a hot spot 209 onthe media.

The NFT 210 is a near-field optics device configured to generate localsurface plasmon resonance at a designated (e.g., design) wavelength. TheNFT 210 is generally formed from a thin film of plasmonic material(e.g., gold, silver, copper) on a substrate. In a HAMR slider 202, theNFT 210 is positioned proximate the write pole of the writer 206. TheNFT 210 is aligned with the plane of the ABS 215 parallel to theread/write surface of the magnetic medium 211. The NFT 210 achievessurface plasmon resonance in response to the incident electromagneticenergy. The plasmons generated by this resonance are emitted from theNFT 210 towards the magnetic medium 211 where they are absorbed tocreate the hot spot 209. At resonance, a high electric field surroundsthe NFT 210 due to the collective oscillations of electrons at the metalsurface (e.g., substrate) of the magnetic medium 211. At least a portionof the electric field surrounding the NFT 210 gets absorbed by themagnetic medium 211, thereby raising the temperature of the spot 209 onthe medium 211 as data is being recorded.

As was discussed previously, heat produced by a write coil of a writercauses thermal expansion of the slider at and proximate the writer,resulting in WIWP. WIWP must generally be accounted for when the writecoil(s) are active in order to maintain a desired head-medium spacingduring write operations. In the case of heat-assisted magneticrecording, excitation of the NFT 210 generates appreciable heat, whichcontributes to thermal expansion of the slider at and proximate to theNFT 210 (e.g., Laser-Induced-Writer-Protrusion or LIWP). Because the NFT210 is either adjacent or connected to the writer 206 (e.g., via a heatsink in contact with a write pole of the writer 206), cooling of thewriter 206 using a writer cooling arrangement of the present disclosureadvantageously results in cooling of the NFT 210 (and a reduction ofLIWP).

FIG. 3 illustrates a writer 300 which incorporates a write coil coolingarrangement in accordance with various embodiments. The writer 300 shownin FIG. 3 includes a write coil arrangement 301, a first return pole306, and a second return pole 308. A write pole 304 is disposed betweenthe first return pole 306 and the second return pole 308. A readerarrangement 309 is shown proximate the first return pole 306. The readerarrangement 309 includes a reader element disposed between a pair ofreader shields.

In the embodiment shown in FIG. 3, the write coil arrangement 301includes an upper write coil 302 and a lower write coil 303 positionedbelow the upper write coil 302. As shown, the coil arrangement 301 is ofa double-layer pancake design. It is understood that coolingarrangements of the present disclosure can be implemented for coolingwrite coil arrangements having a single-layer pancake design or ahelical design, for example. The upper and lower write coils 302 and 303each have a generally circularly-shaped periphery and a width definedbetween the first and second peripheral surfaces.

As is shown in the embodiment of FIG. 3, the upper write coil 302includes a pair of cooling arms 310 and 312 that project laterally fromperipheral surfaces of the upper write coil 302 and extend along the ABS305 of the slider. A first cooling arm 310 projects from a peripheralsurface of the upper write coil 302 in a first cross-track direction ofthe slider, and a second cooling arms 312 projects from a peripheralsurface of the upper write coil 302 in a second cross-track direction(opposite that of the first cross-track direction). The first coolingarm 310 includes a media-facing surface 311 and the second cooling arm312 includes a media-facing surface 313. The media-facing surfaces 311and 313 of the first and second cooling arms 310 and 312 are situated atand extend along the ABS 305 of the slider.

The lower write coil 303 includes a pair of cooling arms 320 and 322that project laterally from peripheral surfaces of the lower write coil303 and extend along the ABS 305 of the slider. The first cooling arm320 projects from a peripheral surface of the lower write coil 303 inthe first cross-track direction of the slider, and the second coolingarm 322 projects from a peripheral surface of the lower write coil 302in the second cross-track direction. The first cooling arm 320 includesa media-facing surface 321 and the second cooling arm 322 includes amedia-facing surface 323. The media-facing surfaces 321 and 323 of thefirst and second cooling arms 320 and 322 are situated at and extendalong the ABS 305 of the slider. In the embodiment shown in FIG. 3, thecooling arms 310, 312, 320, and 322 extend beyond peripheral edgesurfaces of the respective upper and lower write coils 302 and 303.

In conventional writer designs, the writer coils are recessed into thebody of the slider and are not exposed to the ABS. Conventional writerdesigns can employ cooling arrangements that dissipate heat into thebody of the slider. A write coil cooling arrangement of the presentdisclosure advantageously exposes the writer coil to the ABS of theslider, which is the most significant path to transfer heat out of theslider. For example, the increased air pressure at the ABS providesappreciable cooling of the writer coil, which is a heat transfer paththat is more resistive in conventional writer designs.

FIG. 4 is a view of an upper write coil 302 incorporating a coolingarrangement in accordance with various embodiments. The upper write coil302 includes a number of coil turns (e.g., 3 turns), each of whichincludes a thinned section 314 at or proximate the ABS 305. The thinnedsections 314 of the coil turns are locations of the upper write coil 302where the greatest amount of heat is generated. In the embodiment shownin FIG. 4, and outermost coil turn 302′ has a larger thinned section314′ relative to the thinned sections 314 of the inner coil turns. Thisexpanded thinned section 314′ extends along the ABS 305 and connectswith the cooling arms 310 and 312. It is noted that, according to someembodiments, the thinned section 314′ of the outermost coil turn 302′can be of the same size as that of the inner coil turns. For example,and with reference to FIG. 5, the thinned section 314′ of the outermostcoil turn 302′ is of the same size as that of the inner coil turns. Inthe embodiment shown in FIG. 5, the thinned section 314′ of theoutermost coil turn 302′ is recessed somewhat from the ABS 305 (e.g., by≤0.5 μm) but still subject to cooling during write operations.

FIG. 6 is an exploded view of a cooling arm 320 of a lower write coil303 in accordance with various embodiments. The cooling arm 320 shown inFIG. 6 has a length, l, a height, h, and a thickness, t. The length, l,is a distance in a cross-track direction defined between a peripheralsurface 307 of an outermost turn 303′ of the write coil 303 and aterminal end surface 327 of the cooling arm 320. The length, l, of thecooling arm 320 can range between about 10 and 50 μm (e.g., betweenabout 40 and 50 μm). The height, h, is the distance defined between amedia-facing surface 321 of the cooling arm 320 and a non-media-facingsurface 325. The height, h, of the cooling arm 320 can range betweenabout 3 and 10 μm. The thickness, t, of the cooling arm 320 can be thesame as that of other portions of the lower write coil 303 or can be ofa different thickness. For example, the thickness, t, of the cooling arm320 can range between about 0.5 and 10 μm.

It is noted that, although not shown in FIG. 6, a second cooling arm ofthe lower write coil 303 (e.g., arm 322 shown in FIGS. 7 and 8)typically has length and height dimensions (l, h) different from thoseof the cooling arm 320 shown in FIG. 6. The dimensions of the coolingarms of the upper write coil (see arms 310 and 312 of coil 302 in FIGS.4 and 5) can be within the same range as those specified for the lowerwrite coil 303 described with reference to FIG. 6.

According to some embodiments, the lower write coil 303 can have athickness of about 600 nm. The cooling arms 320 and 322 (see FIGS. 7 and8) may be formed at the same time as the lower write coil 303. As such,the cooling arms 320 and 322 can have a thickness, t, of about 600 nm(e.g., same thickness as the lower write coil 303). In some embodiments,the upper write coil 302 (see, e.g., FIGS. 4 and 5) has a thicknessgreater than that of the lower write coil 303, such as about 1 μm. Thecooling arms 310 and 312 (see FIGS. 9 and 10) may be formed at the sametime as the upper write coil 302. As such, the cooling arms 310 and 312can have a thickness, t, of about 1 μm or greater (e.g., same thicknessas the upper write coil 302). It is noted that length, l, and height, h,dimensions may be unique to each cooling arm of the upper and lowerwrite coils 302 and 303. It is further noted that, according to someembodiments discussed below, the cooling arms 310, 312, 320, and 322 canhave a thickness, t, greater than that of their respective upper andlower write coils 302 and 303.

FIGS. 7 and 8 show views of a lower write coil 303 incorporating coolingarms 320 and 322, while FIGS. 9 and 10 show views of an upper write coil302 incorporating cooling arms 310 and 312 in accordance with variousembodiments. In FIGS. 7 and 8, the cooling arm 320 is the same as thatshown in the exploded view of the lower write coil 303 illustrated inFIG. 6. The cooling arm 322 has length, l, and height, h, dimensionsdifferent from those of cooling arm 320. Each of the cooling arms 320and 322 has a media-facing surface 321 and 323 situated at and extendingalong the ABS 305. In a similar manner, cooling arm 310 of the upperwrite coil 302 shown in FIGS. 9 and 10 has length, l, and height, h,dimensions different from those of cooling arm 312. Each of the coolingarms 310 and 312 has a media-facing surface 311 and 313 situated at andextending along the ABS 305. Notwithstanding the differentconfigurations and dimensions of cooling arms shown in the figures, eachcooling arm is configured to dissipate heat generated in a coil of thewriter to the ABS 305, such that each cooling arm is subject toincreased cooling at the ABS 305.

FIGS. 11 and 12 illustrate embodiments of a write coil in accordancewith alternative embodiments. FIG. 11 shows a write coil 302 having amedia-facing surface situated at and extends along the ABS 305 of theslider. More particularly, the write coil 302 includes a number of turnseach having a thinned section 314. The thinned section 314′ of theoutermost turn 302′ is situated at and extends along the ABS 305.Although the write coil 302 shown in FIG. 11 excludes the cooling armsof other embodiments, significant cooling of the write coil 302 isachieved through cooling of the thinned section 314 of the write coil302 at the ABS 305. As was discussed previously, the thinned section 314is the portion of the write coil 302 where the greatest amount of heatis generated.

FIG. 12 illustrates a write coil 302 having truncated cooling arms 310and 312 situated at and extending along the ABS 305 of the slider. Inthe embodiment of FIG. 12, the truncated cooling arms 310 and 312 serveto increase the surface area of the thinned section 314′ of theoutermost coil turn 302′ that is exposed to the ABS 305 and subjected toincreased cooling. In the embodiment shown in FIG. 12, the write coil302 has a width, w, defined between peripheral edges 314 and 315, andthe truncated cooling arms 310 and 312 have a length, l, constrainedwithin the width, w, of the write coil 302.

FIGS. 13 and 14 illustrate an upper write coil 302 of a writer thatincorporates thickened cooling arms 310 and 312 in accordance withvarious embodiments. FIG. 15 shows a lower write coil 303 thatincorporates thickened cooling arms 320 and 322 in accordance withvarious embodiments. As is shown in FIGS. 13 and 15, each of the coolingarms 310, 312, 320, and 322 has a thickness, t₁. As is also shown inFIGS. 13 and 15, each of the upper and lower write coils 302 and 303 hasa thickness, t₂. As was discussed previously, the upper write coil 302has a thickness, t₂, of about 1 μm, and the lower write coil 303 has athickness, t₂, of about 600 nm. The thickness, t₁, of the cooling arms310, 312, 320, and 322 can range between about 1.5 to 4 times therespective thickness, t₂, of the upper and lower write coils 302 and303. For example, the thickness, t₁, can range between about 1.5 μm and4 μm (e.g., between about 2-3 μm). It is noted that the thickness, t₁,of the cooling arms 310, 312, 320, and 322 is typically related to thethickness, t₂, of the upper and lower write coil 302 and 303.

FIGS. 16 and 17 illustrate an upper write coil 302 of a writer thatincorporates thickened cooling arms 310 and 312 which further include acoating or layer 330 of conductive material that differs from thematerial used to fabricate the cooling arms 310 and 312 in accordancewith various embodiments. FIG. 18 illustrates a lower write coil 303that incorporates thickened cooling arms 320 and 322 which furtherinclude a coating or layer 330 of conductive material that differs fromthat used to fabricate the cooling arms 320 and 322. In FIGS. 16-18, thecooling arms 310, 312, 320, 322 can have thicknesses describedpreviously with regard to the embodiment shown in FIGS. 13-15. Inaddition, the cooling arms 310, 312, 320, and 322 can include a coatingor layer 330 of an ABS-friendly metal or metal alloy. An ABS-friendlymaterial is one that enhances electrical, mechanical, and/or chemicalperformance of the write coil within the environment at the ABS.Suitable metals or metal alloys include NiFe and Cr, for example.

Typically, the upper and lower write coils 302 and 303 are formed fromcopper. Although copper is an exceptional conductor, copper can besubject to corrosion at the ABS over time. Covering the cooling arms310, 312, 320, and 322 with an ABS-friendly metal or metal alloy 330prevents or reduces the likelihood of corrosion of the copper coilstructure when exposed to the ABS. Moreover, exposing an electricallycharged copper coil structure to the ABS can result in development of alarge voltage potential between the coil structure and the disk surface.Coating the cooling arms 310, 312, 320, and 322 with an ABS-friendlymetal or metal alloy 330 that is less conductive than copper can reducethe voltage potential between the writer coils and the disk surface.

According to some embodiments, the material 330 used to coat or coverthe cooling arms 310, 312, 320, and 322 is an electrically insulatingand thermally conducting material. In some embodiments, the cooling arms310, 312, 320, and 322 can be formed from the electrically insulatingand thermally conducting material. Suitable thermally conductivedielectric materials include MgO and AlN. Such materials provide goodthermal conduction while electrically insulating much of the copper coilstructure exposed to the ABS, thereby reducing the voltage potentialbetween the writer coils 302 and 303 and the disk surface.

In other embodiments, the cooling arms 310, 312, 320, and 322 can beelectrically insulated from, but thermally coupled to, the write coils302 and 303. For example, and with reference to FIG. 19, a thermallyconductive dielectric material 340 is disposed between the write coil302 and the cooling arm 310. In particular, the thermally conductivedielectric material 340 (e.g., MgO or AlN) is disposed between theoutermost turn 302′ of the write coil 302 and the cooling arm 310. Inother embodiments, commonly employed dielectric materials, such asalumina or silica, can be used to electrically isolate the cooling arm310 from the write coil 302. The embodiment shown in FIG. 19 providesfor good thermal conduction of heat from the writer coils 302 and 303 tothe cooling arms 310, 312, 320, and 322 while electrically isolating thecooling arms 310, 312, 320, and 322 from the writer coils 302 and 303,thereby reducing the voltage potential between the writer coils 302 and303 and the disk surface.

Numerical modeling was performed to demonstrate the efficacy of a writercooling arrangement according to an embodiment of the disclosure. Thefollowing data shows significant improvement in several performanceparameters of a writer that incorporates cooling arms when compared to aconventional writer (i.e., no cooling arms and coils recessed into thebody of the slider with no exposure to the ABS). A subset of themodeling results data is provided below in Table 1:

TABLE 1 Baseline Cooling Arms Parameter Design Design Delta Ratio WIWP3.82 nm 3.26 nm −0.57 0.85 WIWP Slope 2.31 A/mW 2.10 A/mW −0.21 0.91WIRP 2.24 nm 1.89 nm −0.35 0.84 Reader Recession 1.82 nm 0.93 nm −0.890.51 to Close pointThe data of Table 1 demonstrates that the writer with cooling armsdesign provided a 15% decrease in Writer-Induced-Writer-Protrusion(WIWP) and a 9% reduction in WIWP slope over a conventional (baseline)design. The data also demonstrates that the writer with cooling armsdesign provided a 16% reduction in Writer-Induced-Reader-Protrusion(WIRP) and a 49% reduction in reader recession to the close point duringwriter heater operation

Systems, devices or methods disclosed herein may include one or more ofthe features structures, methods, or combination thereof describedherein. For example, a device or method may be implemented to includeone or more of the features and/or processes above. It is intended thatsuch device or method need not include all of the features and/orprocesses described herein, but may be implemented to include selectedfeatures and/or processes that provide useful structures and/orfunctionality.

Various modifications and additions can be made to the disclosedembodiments discussed above. Accordingly, the scope of the presentdisclosure should not be limited by the particular embodiments describedabove, but should be defined only by the claims set forth below andequivalents thereof.

What is claimed is:
 1. An apparatus, comprising: a slider configured tointeract with a magnetic recording medium and comprising an air bearingsurface (ABS); a writer provided on the slider and comprising a writecoil and a media-facing surface exposed at the ABS; a plurality ofcooling arms projecting laterally from the write coil and having athickness that ranges from about 0.5 to 10 μm, each of the plurality ofcooling arms extending along, and exposed at, the ABS; and a coating ora layer covering at least the plurality of cooling arms, the coating orlayer comprising material that is less conductive than material of thewrite coil.
 2. The apparatus of claim 1, wherein: the write coilcomprises copper; and the coating or layer comprises material that isless conductive than copper.
 3. The apparatus of claim 1, wherein thecoating or layer comprises electrically insulating and thermallyconducting material.
 4. The apparatus of claim 1, wherein the coating orlayer comprises MgO or AlN.
 5. The apparatus of claim 1, wherein writecoil and the cooling arms are formed from the same material.
 6. Theapparatus of claim 1, comprising a thermally conductive dielectricmaterial disposed between the write coil and the cooling arms.
 7. Theapparatus of claim 6, wherein the thermally conductive dielectricmaterial comprises MgO, AlN, alumina or silica.
 8. The apparatus ofclaim 1, wherein the cooling arms have a thickness greater than that ofthe write coil.
 9. The apparatus of claim 1, wherein the coating orlayer covering at least the plurality of cooling arms reduces a voltagepotential between the write coil and a surface of the magnetic recordingmedium.
 10. An apparatus, comprising: a slider configured to interactwith a magnetic recording medium and comprising an air bearing surface(ABS); a writer provided on the slider and comprising a write coil and amedia-facing surface exposed at the ABS, the write coil comprising afirst material; and a plurality of cooling arms projecting laterallyfrom the write coil, each of the plurality of cooling arms extendingalong, and exposed at, the ABS; wherein the plurality of cooling armscomprises a second material that is less conductive than the firstmaterial of the write coil.
 11. The apparatus of claim 10, wherein: thefirst material of the write coil comprises copper; and the secondmaterial of the cooling arms is less conductive than copper.
 12. Theapparatus of claim 10, wherein the second material of the cooling armscomprises electrically insulating and thermally conducting material. 13.The apparatus of claim 10, wherein the second material of the coolingarms comprises MgO or AlN.
 14. The apparatus of claim 10, comprising athermally conductive dielectric material disposed between the write coiland the cooling arms.
 15. The apparatus of claim 14, wherein thethermally conductive dielectric material comprises MgO, AlN, alumina orsilica.
 16. The apparatus of claim 10, wherein the cooling arms have athickness greater than that of the write coil.
 17. The apparatus ofclaim 16, wherein the thickness of the cooling arms ranges between about0.5 and 10 μm.
 18. An apparatus, comprising: a slider configured tointeract with a magnetic recording medium and comprising an air bearingsurface (ABS); a writer provided on the slider and comprising: a writepole terminating at or near the ABS; a return pole proximate the writepole; and a write coil arrangement having a media-facing surface exposedto the ABS, the write coil arrangement comprising: lower and upper writecoils comprising an electrically conductive metal or alloy; and aplurality of cooling arms projecting laterally from the lower and upperwrite coils and extending along, and exposed at, the ABS, the coolingarms formed from or covered by a material that is less conductive thanthe electrically conductive metal or alloy of the lower and upper writecoils.
 19. The apparatus of claim 18, wherein the cooling arm materialcomprises an electrically insulating and thermally conducting material.